doi:10.1016/S0304-3940(02)00829-7
Copyright © 2002 Elsevier Science Ireland Ltd. All rights reserved.
Morphology of physiologically identified otolith-related vestibular neurons in cats
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Hui Meng, Hitoshi Sato, Midori Imagawa, Mridha Zakir, Seiji Ono, Keisuke Kushiro, Xialing Zhang, Rishu Bai and Yoshio Uchino
, 
Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan
Received 8 July 2002;
revised 24 July 2002;
accepted 25 July 2002.
Available online 27 September 2002.
Abstract
The morphology of physiologically identified otolith nerve-activated vestibular neurons was investigated using intracellular injections of horseradish peroxidase (HRP). Eleven utricular, 11 saccular and three utricular/saccular nerve-activated vestibular neurons were labeled with HRP. All of these neurons except one were secondary neurons, the exception being a convergent neuron. The labeled neurons were pyramidal, elongated and ovoidal in shape. Most of the labeled cells were medium to large (mean diameter: ≥30 μm). There was no apparent correlation between morphology and the different types of otolith nerve-activated vestibular neurons. Thus, it seems likely that the functional type of vestibular neurons cannot be presumed on the basis of their morphology alone.
Author Keywords: Utriculus; Sacculus; Horseradish peroxidase; Axonal trajectory; Vestibulospinal neuron; Commissural neuron
Fig. 1. Composite drawing of transverse sections containing reconstructed UT nerve-activated neurons (A,B) and SAC nerve-activated neurons (C,D). (A) and (C) were in the middle level of the lateral nucleus, and (B) and (D) were in the rostral level of the descending nucleus. Arrows indicate axons truncated in the vicinity of cell bodies. Cell 25 in (B) and cell 23 in (C) were convergent neurons. AS, acoustic striae; D, descending nucleus; L, lateral nucleus; M, medial nucleus; PH, prepositus hypoglossi nucleus; RB, restiform body.
Table 1. Morphological characteristics and physiologically characterized projections of otolith activated vestibular neurons (cells 1–11, UT-activated neurons; cells 12–22, SAC-activated neurons; cells 23–25, convergent neurons)a

Corresponding author. Tel.: +81-3-33516141, ext. 322; fax: +81-3-33516544; email: y-uchino@tokyo-med.ac.jp